The present invention relates to stainless spheroidal carbide cast iron material, and its object is to provide stainless spheroidal carbide cast iron material wherein just spheroidal vanadium carbide is crystallized at far colder melting temperature than former, and which has special characteristics such as corrosion-resistance, heat-resistance, abrasion-resistance, toughness and processing ability.
With the development of industrial technology, strength, heat-resistance, abrasion-resistance, corrosion-resistance, and processing ability of materials are required to be higher than prior ones in surroundings where the apparatuses are used severely. For example, in an area of injection molding of engineering plastic, reinforcements like FRP and all kinds of additives are added into the ceramic and resin in order to raise strength, fire-resistance and abrasion-resistance of resin moldings. As a result, with the ceramic being fragile, the resin molding system is easy to be abraded because of the reinforcement within the cylindrical resin, and it further becomes easy to corrode with a corrosive gas generated from the additives. Also, since shapes of parts manufactured in all kinds of industries such as car industry are complex, abrasion of manufacturing apparatuses has become more severe than ever.
First, a usage of white cast iron which is strong cast iron can be considered in order to obtain outstanding abrasion-resistance. However, said white cast iron consisting no graphite within its organization has a defect that it is very fragile, being formed with pearlite and cementite. Therefore, it is not easy to obtain outstanding abrasion-resistance in the usage of the white cast iron. That""s why a usage of spheroidal graphite cast iron with toughness, conquering the defect of white cast iron, is on trial.
Spheroidal graphite cast iron wherein a organization of flake graphite crystallized in its organization is spheroidal in shape has outstanding toughness because the organization of crystallized substance in the organizations of metallic materials gives a great influence on toughness. That is to say that generally, the organization of a crystallized substance bonds covalently or couples electroxe2x80x94statically, becoming a facet and platen in shape always when it has a strong anti-metal characteristic. In this circumstance, toughness is weak. Contrarily, when a characteristic of metal is strong, the organization of a crystallized substance bonds metallically, becoming a nonfacet granular or spheroidal dendrite. In these circumstances, toughness is strong due to a dispersion of force even when being given an impact from an outside. In a case of the spheroidal graphite cast iron, it has outstanding toughness because the organization of the flake graphite crystallized within the organization of cast iron is made to be spheroidal in shape with more than 0.04% of magnesium (Mg) being composed. However, it is difficult to hold both strong toughness and abrasion-resistance.
On the other hand, the present inventors have already disclosed on Japanese patent publication No. 11-124651 that alloy cast iron with outstanding abrasion-resistance and impact-resistance can be obtained by crystallizing spheroidal or granular VC system carbide and Fexe2x80x94Cr system carbide within the organization of cast iron.
However, the alloy cast iron disclosed in the Japanese patent publication No. 11-124651 is outstanding in abrasion-resistance and impact-resistance, but it also has a defect that it is a little inferior in corrosion-resistance and heat-resistance.
Also, the present inventors have disclosed on the CIP application of U.S. patent application Ser. No. 09/371,158 that alloy cast iron being superior in abrasion-resistance and impact-resistance, wherein corrosion resistance and heat-resistance which are faults of the alloy cast iron described in the Japanese patent publication No. 11-124651 are improved, can be obtained by means of crystallizing the spheroidal VC carbide into the cast iron organization
The alloy cast iron described in the CIP application of the U.S. patent application Ser. No. 09/371,158, however, requires high temperature melting at approximately 2,000 K or more on the manufacturing process in order to crystallizing just spheroidal VC carbide into the cast iron organization. Therefore, problems such as making lifetime of fireproof furnace ephemeral occur. In addition, since excessive energy is required to maintain the high temperature, it causes soaring of the manufacturing cost.
After continuing a devoted study of the alloy cast iron further, the present inventors then have come to invent that stainless spheroidal carbide cast iron material wherein just spheroidal vanadium carbide is crystallized at far colder melting temperature than former by means of compounding with the specific elements as bubble assistants, and which has special characteristics such as corrosion-resistance, heat-resistance, abrasion-resistance, toughness and processing ability, can be provided